1. Field of the Invention
The present invention relates to a connector used to connect pipes for conveying a fluid, and more particularly, to a plastic male screw connector which is manufactured through injection molding to replace a conventional screw connector made of a costly metallic material with an injecting-molded plastic screw connector so that the manufacturing costs can be reduced.
2. Description of the Related Art
In general, among methods for conveying a fluid, a method of connecting unit pipes and applying a pressure to a fluid so as to convey the fluid to a distant place is most widely used.
In order to connect pipes, connecting methods such as welding, flange coupling, and so forth are used. In this regard, in connecting copper pipes for an air handling unit such as an air conditioner, it is the norm that a connector with threads formed on a connection part is used.
In this way, in the conventional art, in order to connect XL pipes or pipes for an air handling unit, threads are formed on a portion of each pipe so that the pipe can be threadedly assembled by being rotated. However, such a type of connector is vulnerable to a high pressure or a high fluid pressure. Also, in the case where a work space for connecting pipes is narrow, it may be impossible to carry out connection work by rotating the pipes.
In order to solve these problems, research has been conducted for a screw connector with a rotating connection part to allow both pipes to be connected with each other even by not rotating the pipes.
FIG. 1 is an exploded perspective view illustrating the assembling relationship of a conventional screw connector made of a metallic material.
Referring to FIG. 1, a conventional screw connector 1 made of a metallic material includes a body part 10, a rotating connection part 20, a tightening part 30, and a fixed connection part 40, which are assembled with one another.
The body part 10 has a hexagonal bolt head portion 11. A projecting portion 12 is formed on one side of the hexagonal bolt head portion 11, and a large external thread portion 13 and a small external thread portion 14 with a different outer diameter from the large external thread portion 13 are integrally formed on the other side of the hexagonal bolt head portion 11. The projecting portion 12 serves as a portion which is squeezed against and coupled with the rotating connection part 20, and the small external thread portion 14 serves as a portion which is inserted into and threadedly coupled to a pipe. The large external thread portion 13 serves as a portion which is threadedly coupled to the fixed connection part 40.
The rotating connection part 20 is formed on the inner surface thereof with a guide portion (not shown) in the shape of a groove, such that the rotating connection part 20 can be coupled with the projecting portion 12 of the body part 10 while being capable of rotating. Opposite to the guide portion, a thread portion is formed on the inner surface of the rotating connection part 20.
The tightening part 30 is to be placed outside a portion of a pipe which is coupled with the small external thread portion 14. The tightening part 30 functions to tighten once more the pipe coupled with the connector 1 and maintain secure coupling of the connector 1 and the pipe.
The fixed connection part 40 is coupled with the large external thread portion 13, by which the assembly of the connector 1 is completed. In the connector 1, by the rotating function of the rotating connection part 20, interconnection of a shaft and a pipe or interconnection of pipes can be easily implemented without undergoing twisting.
However, the conventional screw connector has a disadvantage in that, since it is made of a metallic material such as copper or stainless steel, it costs high.
An air conditioner for heating and cooling purposes is placed under a higher temperature and a higher pressure than a situation where general pipes are used. Also, in the air conditioner, not a fluid such as water used in a general piping, but a solvent, in which oil capable of being easily vaporized and compressed and with very high chemical reactivity and oil are mixed with the same phase, is frequently used.
If the connector made of a metallic material is used under these conditions, it is difficult to maintain a sealed state due to contraction and expansion characteristics of a metal, and chemical resistance and friction resistance are likely to deteriorate in that fluid flow may be impeded or a pressure load may be induced by corrosion of a connecting portion resulting from the characteristics of a refrigerant used.